The present invention relates to multiphase cleansing bar.
It has long been a desirable goal to deliver some kind of emollient, moisturizer or nutrient benefit component (e.g., Fatty acids, triglycerides, glycerin, petrolatum, or silicone compounds etc.) to the skin through a personal wash composition for moisturization, etc.
In liquid cleansers, for example, cationic hydrophilic polymers such as Polymer JR(copyright) from Amerchol or Jaguar(copyright) from Rhone Poulenc have been used-to enhance delivery of benefit agents (WO 94/03152; and WO 94/03151). In applicants"" recently issued U.S. Pat. No. 5,965,501 to Rattinger et al., separate emollient droplets act as a structure to entrap the benefit agent in concentrated form.
Delivery of benefit agents (e.g., Fatty acids, triglycerides, glycerin, silicone compounds etc.) has proven difficult in bar compositions for a number of reasons. If the benefit agent does not remain sufficiently discrete from other components in the bar composition, for example, the generally hydrophobic benefit agent will interact with the hydrophobic portion of the surfactant compounds in the bar mix rather than be free to deposit on the skin or other substrate. Thus, little or no benefit agent will be free in the final bar (after milling, plodding and extrusion of chips) to be delivered to the skin. Most of the benefit components are liquids and can interact with surfactants to form a liquid crystalline phase. Thus the use of a high level of these benefit agents can make the bar soft, which also leads to difficulty in processing.
U.S. Pat. No. 4,017,574 to Joshi, issued Apr. 12, 1977 discloses a process for making a multicolored soap bar where a coloring agent is dispersed in a meltable solid vehicle and introduced into a base soap material before extrusion to yield a striped soap bar. The meltable solid material may be wax or wax-like and comprise one or more benefit agents with the limitation that the melting point of the solid material is above 100xc2x0 F. and is compatible with the water soluble dye. However, this meltable solid material may not be compatible with the soap base of the bar resulting in cracking and adhesive failure over time.
U.S. Pat. No. 5,154,849 to Visscher et al. issued Oct. 13, 1992, teaches bar compositions containing a silicone skin mildness/moisturizing aid component as small domains. In one embodiment, the silicone component may be mixed with a carrier which is selected to facilitate incorporation of the silicone in the product. The preferred carrier is said to be polyethylene glycol. At column 16, the reference describes that silicone is mixed into melted Carbowax (polyethylene glycol). The mixture is cooled to form flakes and the flakes are preferably added to an amalgamator with the rest of the formulation ingredients. The carbowax carrier material may not be compatible with the soap base of the bar resulting in rheological and chemical incompatibility.
In the subject invention, the benefit agent is distributed in the cleansing bar in adjacent benefit agent rich and poor phases. In a preferred embodiment, the phases are situated along the major axis of the cleansing bar as stripes. Each phase or layer preferably has substantially the same cleansing base such as a syndet base, a natural soap base, or a blend thereof and is both Theologically and chemically compatible. Rheological compatibility is herein defined as having similar flow properties under extrusion processing conditions. Chemical or interphase compatibility is herein defined as the absence of interfacial cracking or splitting and having similar wear rates or mush properties between abutting phases. Such interphase compatibility is believed to be due to the similarity in free energy at the surface of the abutting phases.
In prior art methods, the addition of the benefit components in amalgamator and further processing through the refiners and plodders leads to mixing of the benefit components in the bulk of the formulation. By contrast, the alternating emollient rich and poor phases of the invention do not get mixed because the two phases are coextruded near the cone at the final plodding stage.
In another embodiment of the invention, the chemically compatible emollient rich and emollient poor phases can be melt cast adjacent to each other.
Whether a result of an extrusion or a casting process, the segregation of the phases or domains can lead to higher deposition of the benefit components during the application of the inventive product. Preferably the cleansing base of the adjacent phases, used for the product, is substantially the same, and rheological and interphase compatibility will therefore be maximized.
In the subject invention, applicants have unexpectedly found that, when the cleansing base in which the highest concentration of emollients are found (xe2x80x9cemollient rich phases or layersxe2x80x9d) is positioned adjacent to a rheologically and chemically compatible lower emollient concentration phase or layer of the cleansing bar xe2x80x9c(emollient deficient phase or layerxe2x80x9d), enhanced deposition of benefit agent occurs without the disadvantage of phase incompatibility problems, lather depression and recycling difficulties. The domains can be in the form of stripes, striations, alternating blocks, swirling, random distribution of the benefit domains etc. Preferably the multiphase cleansing bar will be striped as shown in FIGS. 1 and 2. In the specification, the terms emollient deficient phase or layer and emollient poor phase or layer are used interchangeably and mean the same thing as defined above.
Specifically, the invention comprises a multiphase cleansing bar comprising:
(a) a plurality of phases of cleansing material;
(b) each of said cleansing phases being Theologically compatible;
(c) said plurality of phases having at least one emollient rich phase, at least one emollient deficient phase, and at least one interface therebetween;
(d) said emollient rich phase containing an emollient composition in the amount of 0.1 to 50 weight %, said emollient deficient phase containing an emollient composition in the amount of 0 to 25 weight %; and said emollient rich phase having a higher total emollient composition concentration compared to the emollient poor phase.
Preferably the emollient rich and poor phases will have substantially the same cleansing base selected from the group consisting of a syndet base, a soap base, or a mixture thereof.
Preferably the emollient composition concentration in the emollient rich layer based on the total cleansing bar, is 0.5 to 30 weight %, more preferably 1 to 20 weight %. Preferably the emollient composition concentration in the emollient poor phase is 0 to 10 weight %, more preferably 0 to 5 weight %, base on the total cleansing bar. Preferably the emollient composition concentration in the emollient rich phase is 5 times the emollient composition concentration in the emollient poor phase. More preferably the emollient composition concentration in the emollient rich phase is times the emollient composition concentration in the emollient poor phase.
In a preferred embodiment of the invention, the cleansing bar comprises:
(a) a plurality of layers or phases of cleansing material;
(b) each of said cleansing layers having a substantially uniform cleansing base selected from the group consisting of a syndet base, a soap base, or mixtures thereof;
(c) said plurality of layers having alternating emollient rich layers and emollient poor layers;
(d) said emollient rich layers uniformly containing an emollient composition in the amount of 0.1 to 50 weight %, said emollient poor layers uniformly containing an emollient composition in the amount of 0 to 5 weight %; and said emollient rich layers having at least 2 times the emollient composition concentration compared to the emollient poor layers.
The surfactant system or cleansing base may be a pure soap surfactant system having tallowate and/or vegetable oil soaps such as palmate, cocoate, palmkernelate, any other vegetable oil soap or a mixture of these at any ratio. Preferably the tallowate/cocoate blend is used in the ratio range of 90/10 to 50/50. Most preferably it is in the ratio range of 90/10 to 60/40. Preferably the vegetable oil is selected from the group consisting of palm oil, coconut oil, palm kernal oil, palm stearin, and hydrogenated rice bran oil.
The surfactant system also may comprise a synthetic detergent system (xe2x80x9csyndetxe2x80x9d). Preferably the syndet system comprises:
(a) a first synthetic surfactant which is an anionic surfactant; and/or
(b) a second surfactant selected from -the group consisting of a second anionic surfactant different from the first, a nonionic, an amphoteric and mixtures thereof.
A particularly preferred syndet surfactant system comprises acyl isethionate as the first anionic and a sulfosuccinate or a betaine surfactant or mixtures of the two as the second surfactant. Alternatively the surfactant system may be a blend of pure soap and synthetic surfactants.
In accordance with these and other aspects of the invention, the invention will now be described with reference to the accompanying drawings where like numerals represent like features.